Gelled propellant compositions useful in aerosol dispensers



3,461,079 Patented Aug. 12, 1969 3,461,079 GELLED PROPELLANTCOMPOSITIONS USEFUL IN AEROSOL DISPENSERS Irving B. Goldberg, 425 W.Aldine, Chicago, Ill. 60657 No Drawing. Filed June 11, 1964, Ser. No.374,268

Int. Cl. C09k 3/30 US. Cl. 252-305 3 Claims ABSTRACT OF THE DISCLOSURE Acomposition set in the form of a gel which is stable under conditions oftemperature and pressure that render normally gaseous aerosol propellanta liquid and will free the aerosol propellant as a gas upon reduction ofpressure consisting of aerosol propellant in liquid form incorporatedinto a soap of fatty acids having 5 to 14 carbon atoms set as a solidusing oleic acid as a gelling catalyst.

This invention relates to aerosol propellant compositions. Moreparticularly, it relates to compositions containing liquefied gaseouspropellants in a semi-solid form. Still more particularly, it relates togelled propellant compositions and to combinations of propellantcompositions and containers which are particularly adapted fordispensing substantially dry gases as well as liquids and solidssuspensions from said container.

In accordance with this invention, compositions areprepared whichcomprise a liquid, produced by liquefaction of a material which is a gasat normal temperatures and pressures, admixed with a soap to form gelledpropellant compositions for use in valved containers, for example,aerosol dispensers.

Aerosol dispensers generally operate at pressures up to about 100 poundsper square inch gauge, although containers for the retail trade capableof holding, for exam le, 14 ounces of liquid, are available which can beoperated safely at higher pressures. The usual procedure today is tointroduce into such an aerosol dispenser a propellant or propellantmixture capable of existing at room temperature and at a predeterminedpressure, as an equilibrium mixture of liquid and gas.

Such aerosol dispensing systems have exhibited numerous disadvantages.The containers have a limited range of positions from which liquid otherthan the propellant can be dispensed, for example, as an atomized spray.Another disadvantage is the so-called spattering or dispensing ofdroplets of liquefied propellant together with the liquid intended to bedispensed, a result which can have deleterious effect, for example, whenthe product dispensed is a coating composition.

A further serious disadvantage of the aerosol systems has been thereduction in vapor pressure of the system during dispensing unless thedischarge is limited to short periods of dispensing, i.e., short bursts.When dispensing is uninterrupted, the continuous vaporization of gasresults in cooling of the liquid from which the gas is evolved. As thetemperature is lowered, the vapor pressure of the system is reduced withthe result that the spray pattern may be altered or the entire contentsof the container cannot be dispensed without such a period of delay asis necessary to allow the container contents to return to atmospherictemperature.

Now it has been discovered that the disadvantages can be overcome byintroducing into valved dispensing containers a propellant compositioncomprising an aerosol liquid and metal soap of relative short chain orlower fatty acids, which combination sets to a gel. In this propellantcomposition, the liquefiable propellant generally constitute-s between50% and 99.5% by weight of the compositions.

Propellants useful in this invention may be varied depending upon thenature of the liquid solution, or the liquid medium of a solidssuspension, etc., to be dispensed. Useful propellants, generallyspeaking, are the relatively water insoluble, saturated aliphatichydrocarbons'and partially halogenated hydrocarbons having vaporpressures in the range between about 5 pounds to about 200 pounds p.s.i.gauge at 70 F., and preferably in the range betwen about 30 pounds andabout pounds p.s.i. gauge. The propellants maybe formed of a mixture oftwo or more such compounds which, although the individual propellantsmay have vapor pressures outside the desired range, have, when combined,a vapor pressure within the stated ranges.

Straight chain saturated aliphatic hydrocarbons having vapor pressuresuitable for the purpose are propane, butane, isobutane and cyclobutane.Other propellants useful alone or in admixture with other propellantsare the saturated fluorinated or chlorinated or chlorfluorinatedhydrocarbons, for example, the substantially water-insoluble halogenatedalkanes having not more than two carbon atoms and at least one fluorineatom such as 1,1- difluorethane, l-monochlor, l-difluorethane,monofluortrichlormethane, monochlordifluormethane,dichlordifluormethane, 1,2-dichloro, 1,1,2,3-tetrafluorethane, and thelike.

Soaps employed to form the gelled propellant compositions may be varieddepending upon the nature of the liquid to be dispensed or the liquidcomponent of material such as paint, insecticidal compositions, etc.,which are intended to be dispensed.

In choosing an appropriate soap, the action or fatty acid anion or bothmay be varied to obtain the desired degree of solubility or insolubilityof the soap in the fluid material being dispensed. In general, theuseful soaps are metallic soaps of lower fatty acids selected from thegroup of fatty acids having about 5 to about 14 carbon atoms in thealiphatic hydrocarbon group.

In general, the higher the number of carbon atoms in the saturated orunsaturated aliphatic chain of the fatty acid anion, the greater theinsolubility of the soap in an aqueous medium or in solvents. Usefulacids for the purposes of this invention are the saturated orunsaturated fatty acids having about 5 to about 14 carbon atoms in thealiphatic hydrocarbon group, preferably about 8 to about 11 carbonatoms. Useful saturated fatty acids are valeric, caproic, heptoic,caprylic, n-nonyl-ic, capric, undecylic, lauri c, myristic, etc., acids.Useful unsaturated fatty acids are, for example, decenoic, 2-hexenoic,octenoic, etc., acids.

As was stated previously, the solubility characteristics of the soap maybe controlled through the choice of cation. In general, ammonium cation,alkali metal cations such as sodium, potassium, lithium, alkaline earthmetal cations such as calcium, barium and magnesium, etc., aluminum,lead, etc., cations are useful in forming the soaps. For example,ammonium myristate is soluble in methanol and ethanol and insoluble inether, benzene, acetone, etc. Alkali metal soaps of lower fatty acids,for example, sodium laurate and certain alkaline earth metal salts oflower fatty acids have limited solubility in water and organic solvents.Aluminum and magnesium laurate have limited solubility in both aqueousmedia and organic solvents. Such a variation in properties makesmixtures of soaps a preferable embodiment of the invention becausemixtures can be so combined as to give insolubility in a broad spectrumof mediums which may be dispensed.

When preparing a propellant composition, from about /2 by weight toabout 50% by weight of the total propellant composition may be soap.Such amounts of soap may be introduced into a container simultaneouslywith or consecutively with the propellant liquid. Such a mixture willgel in the container. On other other hand, the gelled composition may bepreformed, stored under appropriate conditions and transferred to acontainer as a solid gelled composition and the container closed byconventional procedures. When mixing propellant liquid and appropriateamounts of soap, the gelling may be accelerated by addition to themixture of a catalyst, for example, oleic acid or other higher fattyacids.

When propellants embodying this invention are used to dispense liquids,the gelled compositions may have a specific gravity such that thecomposition will assume the same position relative to the liquid to bedispensed as a conventional aerosol or Freon liquid and the liquid to bedispensed will be forced from the container through a so-called dip tubewhich extends to the bottom of the valve container. Gelled compositionsmay also have a specific gravity such that the gelled mixture positionsitself at the bottom of the container, in which event a short clip tubeor extension of the valve casing need only extend a sufficient distanceinto a container to permit dispensing of substantially all of the liquidmaterial present in the container.

In still other instances the gelled propellant may be used alone in thecontainer to dispense a dry gas. In such cases, the valve need not havea dip tube at all.

A gelled propellant composition functions to eliminate dispensing ofliquid propellant droplets regardless of the positioning of thecontainer valve with respect to the bottom of the container. It alsoeliminates dispensing of droplets of liquid propellant because only dryvaporized gas is free to mix with the liquid to be dispensed, or in thecase of dispensing only propellant, only dry gas is dispensed.

The invention will be further understood from the following exampleswhich are provided without any intention that the invention be limitedthereto.

Example I A mixture of 7.6 parts by weight of aluminum caprylate soapand 2.3 parts by weight of oleic acid was added to 142 parts by weightof propellant maintained at a temperature of F., said propellantconsisting of 126.8 parts by weight of dichlordifluormethane (Freon 12),15.2 parts by weight of perchlorethylene which provides a composition of142 parts by weight under a pressure of between about 40 pounds andabout 50 pounds gauge when the contents of a valved container attainsroom temperature of approximately 70 F.

A valved container A was filled with 151.9 grams of propellantcomposition which provided 142 grams of propellant. An identical valvedcontainer B was filled with 142 grams of liquefied propellant consistingof 126.8 parts of dichlorfiuormethane (Freon 12) and 15.2 parts byweight of perchlorethylene so that the vapor pressures in the containerswere substantially equal at 70 F.

In order to test the comparative delivery of the two containers, theywere arranged to spray simultaneously on a cycle involving intermittentdispensing over a period of five minutes, the intermittent sprayingbeing for a period of five seconds followed by a wait of ten seconds. Atthe end of the five minute period there was a ten minute delay beforethe spray cycle was repeated.

When the spray time for container B totaled 1340 seconds, all of thepropellant was spent. After a wait of one hour, the container exhibitedno spraying ability.

When the spray time for container A, i.e., the container with gelledpropellant composition, totaled 1760 seconds, the container indicatedthat propellant was spent. However, after a wait of one hour, thecontainer A sprayed for an additional 95 seconds. After another hoursdelay, the container A sprayed for 20 seconds and after a third wait ofone hour, the container A sprayed for 15 seconds.

The container A, containing gelled propellant, thus showed initialspraying time approximately one third greater than conventionalpropellant and an overall dispensing capacity of approximately 40%greater than container D which is representative of conventionaldispensing container.

Example II A mixture of 7.6 parts by weight of aluminum caprylate soapand 2.3 parts by weight of oleic acid was added to 142 parts by weightof propellant maintained at a temperature of 0 F., said propellantconsisting of 126.8 parts by weight of dichlordifluormethane (Freon 12),15.2 parts by weight of perchlorethylene which provides a composition of142 parts by weight under a pressure of between about 40 pounds andabout 50 pounds gauge when the contents of a valved container attainsroom temperature of approximately 70 F.

The gelled propellant composition was formed in the container and anaqueous solution was added to substantially fill the container. Thecontainer then was closed by a valve of the type conventionally used foraerosol dispensing.

This container dispensed the aqueous solution in an appropriate spraypattern until substantially all of the solution had been discharged fromthe container.

In using the compositions of this invention, the soap and propellant andany petroleum distillate vapor depressant which may be added areintroduced into the container wherein they form the gelled compositionwith the propellant when the propellant is added. The propellant may beintroduced before or after the dispensing valve is attached to thecontainer.

While a detailed description of the composition and package has beenprovided, it should be understood that numerous modifcations may beeffected without departing from the spirit and scope as indicated in theappended claims.

I claim:

1. A composition set in the form of a gel which is stable underconditions of temperature and pressure that render a normally gaseousaerosol propellant a liquid and will free said aerosol propellant as agas upon reduction in the pressure consisting essentially of an aerosolpropellant in liquid form selected from the group consisting ofliquefiable hydrocarbons and halogenated hydrocarbons which are gases atatmospheric temperature and pressures, between 1% and 4% by weight ofthe composition of oleic acid, said aerosol propellant and oleic acidbeing incorporated into a soap set as a solid which comprises lowerfatty acid anion selected from the group consisting of fatty acidshaving 5 to 14 carbon atoms in the aliphatic hydrocarbon group and acation selected from the group consisting of alkali metal, alkalineearth metal, aluminum, lead and ammonium cations.

2. The method of producing a composition which can be held as a gel atelevated pressures and will upon reduction of pressure free aerosolpropellant in gaseous form which comprises admixing a liquid form ofnormally gaseous aerosol propellant selected from the group consistingof liquefiable hydrocarbons and halogenated hydrocarbons which are gasesat atmospheric temperatures and pressures, under conditions oftemperature and pressure to maintain said propellant a a liquid withbetween about 1% and 4% by weight of the composition of higher fattyacid catalyst for acceleration of gelation and a soap which compriseslower fatty acid anion selected from the group consisting of fatty acidshaving 5 to 14 carbon atoms in the aliphatic hydrocarbon group and acation selected from the group consisting of alkali metal, alkalineearth metal, aluminum, lead and ammonium cations.

3. The method according to claim 2 in which said higher fatty acidcatalyst is oleic acid.

(References on following page) References Cited UNITED STATES PATENTSRay 447 Browning 252305 X Hunn 252-316 x 5 Cardwell et a1 2528.55 Fastet a1. 166-42 X Ira-1050 UNITED STATES PATENT OFFICE (s/ss) CERTIFICATEOF CQRRECTION PatentNo; 3,u61,o79 Dated August 12, 1969 Inventor(s)Irvine; B. Goldberg It is certified that error eppears in theabove-identified patent a nd that said Letters Patent are herebycorrected as shown below:

Column 2, line 27, '53" shoul d be 2-,- column 2, line 3H,

"action" should be cation column'3, line 56, "dichlorfluormethane"should be dichlor'difluor'methane column 4, line 4, "D" should be Bcolumn 4, line 36,

"modifcations" should be modifications SIGNED AND SEALED APR 2 81970 EALAttcst;

dward M. Fletcher, Ir. WILLIAM E, *SOHUYIJER,

fi 5 Offifier Commissioner of ratanta

